Monopulse receiver for a four arm log spiral antenna

摘要

A method of apparatus for determining the rectangular coordinate direction angles of a source of radio signals received by a four arm log spiral antenna and then processed by a beam-forming network to simultaneously generate both sum and difference modes. The sum and difference IF signals are heterodyned to a sum IF signal SIGMA and a difference IF signal DELTA . The SIGMA and DELTA signals are combined in an IF network to provide three IF signals, namely SIGMA + DELTA , SIGMA -j DELTA and j SIGMA , which are thereafter amplitude limited by respective limiting amplifiers. The three limited signals are processed by two phase detectors, which generate voltages Ex and Ey corresponding respectively to the sine of the phase angles of the limited signals SIGMA + DELTA and SIGMA -j DELTA relative to the limited signal j SIGMA . Since each combination of the voltages Ex and Ey corresponds to a single set of rectangular coordinate direction angles, these direction angles are easily determined by a conventional computer.